Figure 4From: Hydrothermal phase transformation of hematite to magnetiteMixture of α-Fe 2 O 3 and Fe 3 O 4 particles precipitated in the hydrothermal system at 200 °C at different times. (a) 2 h, (b) 5 h, (c) 7 h, and (d) 9 h.Back to article page